OFFSET
3,2
COMMENTS
Cycles have length at least 2, and may repeat vertices but not edges.
Cycles p,q are equivalent if the vertex-edge sequence of q can be made by rotating or reversing that of p. The multigraphs have no loops.
LINKS
Simon R. Donnelly, Table of n, a(n) for n = 3..92
Simon R. Donnelly, Python program to compute a(n)
Eric W. Weisstein, Multigraph
EXAMPLE
For n=6 there are three possible arrangements:
1,1,4: 40 cycles,
1,2,3: 28 cycles,
2,2,2: 33 cycles,
so a(6) = 28.
PROG
(Python) See links.
CROSSREFS
KEYWORD
nonn,walk,hard
AUTHOR
Simon R. Donnelly, Oct 09 2015
STATUS
approved